Sunday, December 19, 2010

Magic and muggle in Austria speciation meeting

Set against a backdrop of vineyards and castles, and held in the summer palace of the Hapsburgs in Laxenburg, was the First European Conference on Speciation Research, organized by Ulf Dieckmann and Ake Brannstrom. Thirty or so talks and many posters fomented a great environment for argument and debate – with or without liquid encouragement.

A principle item of argument was the role of “magic traits” in speciation. The term was originally coined by Sergey Gavrilets in a derisive way to suggest the implausibility of natural populations having traits (or genes) that were under divergent natural selection and also influenced mate choice. Traits/genes like this make speciation, particularly sympatric speciation, much easier and frequently appear in theoretical models demonstrating that sympatric speciation is “plausible.” The funny thing was that empiricists quickly pointed to a large number of traits that seemingly do have these joint effects, including body size in stickleback, beak size in finches, color in butterflies and hamlet fishes, and habitat choice in herbivorous insects. And so magic traits quickly became a rallying point for people studying speciation in sympatry or parapatry: i.e., speciation with gene flow. Now many empirical studies invoke the existence of apparent magic traits in their study system as a way of suggesting an easy, perhaps even inevitable route to speciation. And new theoretical models are now invoking magic traits in a proactive way, rather than cloaking them in alternative genetic structures and explained them away in an apologetic fashion.

So what’s to debate? The first point was that some people felt the term shouldn’t be invoked because it implied that such traits are not believable – when they may actually be common. Others at the meeting disliked the term because it wasn’t defined precisely – although several people are working on doing precisely this. My own point of concern was partly related to this ambiguity. In particular, just how much of the reproductive isolation evolving between two species must such a dual-effect trait explain to warrant the term “magic.” To me, magic implied something important - perhaps speciation wouldn’t have occurred without the magic trait. But it was pointed out by Maria Servedio that the original definition doesn’t imply any effect size. I resisted this for some time, but then realized that not all magic has to be important. Hermione might use “trivial magic” to make a feather float, whereas she might use “important magic” to save Harry’s life. Both actions are magic but only the latter matters. So maybe we need to distinguish “trivial magic traits” from “important magic traits.” Best of all, however, Eva Kisdi noted that the appropriate antonym for a non-magic trait is clearly a “muggle trait,” and so I realized I loved the term.

And so I stayed out until 2 am drinking and arguing with Maria Servedio, Dan Bolnick, Louis Bernatchez, and Isabelle Olivieri. Then I caught a cab for the airport at 4:30 am, and watched the magic of lightly falling snow illuminated by the light from ancient buildings against the inky backdrop of the pre-dawn sky. Trivial perhaps – but no less magic to a muggle.